582 CYPERACE^. (sedge FAMILY.) 



17. S. polyphyllus, Vahl. Culm usually more leafy; spikelets yellow- 

 brown, ovate, becoming cylindrical, clustered 3-8 togetlier in small heads on the 

 short ultimate divisions of the open decompound umbel ; scales mucronate ; bi-is- 

 tles 6, usualljj twice bent, soft-barbed toward the summit only, about twice the 

 length of the achene. — Swamps and borders of ponds, western N. Eng. to 

 N. C, west to Minn, and Ark. 



9. ERIOPHORUM, L. Cotton-Grass. (PI. 3.) 



Bristles naked, usually very numerous, often silky and becoming greatly 

 elongated. Otherwise as in Scirpus. — Spikelets single or clustered or umbel- 

 late, usually involucrate with erect scale-like bracts, upon a leafy or naked 

 stem ; scales membranaceous, 1 - 3-nerved. Style very slender and elongated, 

 3-cleft. Acliene acutely triangular. (Name composed of fpiou, wool or cotton, 

 and <f)op6s, bearing.) 



* Bristles 6, rust-colored, becoming tortuous and entangled ; culm very leafy, bear- 

 ing numerous spikelets in an involucrate decompound cymose-panicled umbel. 



1. E. line^tum, Benth. & Hook. Culm triangular, leafy (1-3° high); 

 leaves linear, flat, rather broad, rough on the margins ; umbels terminal and 

 sometimes axillar}', loose, drooping, the terminal with a 1 -3-leaved involucre 

 much shorter than the long slender rays ; spikelets oblong, becoming cylindrical 

 (2-4" long), on thread-like drooping pedicels; bristles at maturity scarcely 

 exceeding the ovate green-keeled pointed scales ; achene sharp-pointed. (Scir- 

 pus lineatus, Michx.) — Low grounds, western N. Eng. to Ga., west to Minn, 

 and Mo. 



2. E. cyperinum, L. (PI. 3, fig. 6 - lO, under Scirpus.) (Wool-Grass.) 

 Culm nearly terete (2- 5° high) ; leaves narrowly linear, long, rigid, those of 

 the involucre 3-5, longer than the umbel, the rays at length drooping ; spikelets 

 exceedingly numerous, ovate, clustered, or the lateral pedicelled, woolly at 

 maturity (H-3" long) ; the rust-colored bristles much longer than the pointless 

 scales ; achene short-pointed. (Scirpus Eriophorum, Michx.) — Wet meadows 

 and swamps, Newf. to Fla., west to Minn, and Iowa. Exceedingly variable 

 in the character and size of the umbel, the typical form having the spikelets 

 mostly clustered in small heads. — Yar. laxum has the spikelets scattered, 

 the lateral long-pedicelled. 



* * Bristles 6, crisped, ivhite ; spikelet single, small ; involucre of o)ie short bract. 



3. E. alpinum, L. (PI. 3, fig. l-6.) Culms slender, many in a row 

 from a running rootstock (6-10' high), scabrous, naked; sheaths at the base 

 awl-tipped. — Cold bogs. Lab. to N. Eng., west to Minn. June. (Eu.) 



* * * Bristles very numerous, not crisped, forming dense cottony heads in fruit. 



-)- Culm bearing a single spikelet; involucre none. 



4. E. vaginatum, L. Culms in close tufts (1° high), leafy only at the 

 base, above with 2 inflated leafless sheaths; root-leaves long and thread-form, 

 triangular-channelled ; scales of the ovate spikelet long-pointed, lead-color at 

 maturity. — Cold and high peat-bogs, N. Eng. to Penn., Mich., Minn., and 

 northward. May, .June. (Eu.) 



